Muscle internal clock protein regulates how mice adapt to long-term exercise over time

Low-intensity treadmill training in mice before sleep yields greater benefits for muscle performance and glucose tolerance than training after waking.

• Muscle performance shows diurnal variations, with stronger but less enduring muscles observed before sleep compared to after waking.
• Knockout of circadian clock genes Rev-erbα/β eliminates diurnal variations in muscle performance without impacting muscle mass or activity levels.
• Rev-erb is linked to the suppression of fat breakdown and the promotion of carbohydrate use before sleep.
• The muscle's internal clock, rather than feeding or activity patterns, regulates daily variations in muscle function and training adaptations.

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